U.S. patent application number 10/121113 was filed with the patent office on 2003-10-16 for auto advancing radio frequency array.
Invention is credited to Garabedian, Robert J., Rioux, Robert F..
Application Number | 20030195502 10/121113 |
Document ID | / |
Family ID | 28790248 |
Filed Date | 2003-10-16 |
United States Patent
Application |
20030195502 |
Kind Code |
A1 |
Garabedian, Robert J. ; et
al. |
October 16, 2003 |
Auto advancing radio frequency array
Abstract
A system for ablating lesions in the interior regions of the
human body including a RF catheter and a control system adapted to
facilitate the automatic step deployment of an array-type energy
delivery system positioned within the catheter. The RF catheter and
control system further include an auto array deployment mechanism
coupled to the array-type energy delivery system and an impedance
and temperature monitoring system. In addition, the system includes
a probe positioning device adapted to maintain a RF probe in a
desired orientation during ablation procedures.
Inventors: |
Garabedian, Robert J.;
(Tyngsboro, MA) ; Rioux, Robert F.; (Ashland,
MA) |
Correspondence
Address: |
BINGHAM, MCCUTCHEN LLP
THREE EMBARCADERO, SUITE 1800
SAN FRANCISCO
CA
94111-4067
US
|
Family ID: |
28790248 |
Appl. No.: |
10/121113 |
Filed: |
April 10, 2002 |
Current U.S.
Class: |
606/41 ;
607/101 |
Current CPC
Class: |
A61B 2018/1475 20130101;
A61B 2018/1467 20130101; A61B 90/50 20160201; A61B 18/1482
20130101; A61N 1/06 20130101 |
Class at
Publication: |
606/41 ;
607/101 |
International
Class: |
A61B 018/18 |
Claims
What is claimed:
1. A radio frequency ablation system comprising: a catheter having
an elongate tube and a handle connected to the tube, a needle array
received in the catheter, an array deployment mechanism connected
to the needle array, and a controller connected to the array
deployment mechanism.
2. The ablation system of claim 1 wherein the array deployment
mechanism is servo actuated.
3. The ablation system of claim 1 wherein the controller comprises
a RF power supply connected to the needle array.
4. The ablation system of claim 3 wherein the controller comprises
a temperature or impedance monitoring module connected to the
needle array.
5. The ablation system of claim 4 wherein the needle array
comprises individual tines formed at a distal end of the needle
array, wherein the tines are capable of measuring temperature or
impedance.
6. The ablation system of claim 4 wherein the controller comprises
a drive control module connected to the servo actuated deployment
mechanism.
7. The ablation system of claim 6 wherein the servo actuated
deployment mechanism comprises a servo motor coupled to a driving
member.
8. The ablation system of claim 7 wherein the driving member
comprises a gear.
9. The ablation system of claim 8 wherein the gear comprises a worm
gear, a screw gear or a spur gear.
10. The ablation system of claim 9 further comprising a driven
member connected to the needle array and operably coupled to the
driving member.
11. The ablation system of claim 10 wherein the driven member
comprises a rack or screw drive.
12. A radio frequency probe comprising: an elongate tube, a handle
connected to the tube, a needle array received in the tube and
handle, and a drive mechanism connected to the needle array.
13. The radio frequency probe of claim 12 wherein the drive
mechanism is servo actuated.
14. The radio frequency probe of claim 13 wherein the needle array
comprises individual tines formed at a distal end of the needle
array.
15. The radio frequency probe of claim 14 wherein the tines are
capable of measuring temperature or impedance.
16. The radio frequency probe of claim 15 wherein the servo
actuated drive mechanism comprises a servo motor coupled to a
driving member.
17. The radio frequency probe of claim 16 wherein the driving
member comprises a gear.
18. The radio frequency probe of claim 17 wherein the gear
comprises a worm gear, a screw gear or a spur gear.
19. The radio frequency probe of claim 18 further comprising a
driven member connected to the needle array and operably coupled to
the driving member.
20. The radio frequency probe of claim 19 wherein the driven member
comprises a rack or screw drive.
21. A method for ablating tissue within the body using RF energy
comprising the steps of, (a) inserting a probe having an array-type
energy delivery device into the internal regions of a body to a
treatment site comprising tissue to be ablated, (b) extending a
plurality of tines of the array-type energy delivery device to a
predetermined diameter, (c) applying ablative energy to the
plurality of tines, and (d) automatically advancing the plurality
of tines a predetermined distance after a predetermined tissue
temperature or impedance is reached.
22. The method of claim 21 wherein steps (c) and (d) are repeated
until the plurality of tines of the array type energy delivery
device are fully deployed.
23. The method of claim 22 further comprising the step of ablating
tissue at the treatment site.
24. The method of claim 21 further comprising the steps of
measuring the tissue temperature or impedance at the treatment
site.
25. The method of claim 24 wherein the step (d) further comprising
activating a servo actuated array deployment mechanism coupled to
the array-type energy delivery device when a predetermined tissue
temperature or impedance is reached.
26. The method of claim 20 wherein the step of automatically
advancing the plurality of tines a predetermined distance includes
doing so after a predetermined period of time has elapsed instead
of after a predetermined tissue temperature or impedance is
reached.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to systems and methods for
ablating tissue in interior regions of the human body and, more
particularly, to systems and methods that facilitate the automatic
deployment and placement of a needle array for precise lesion
ablation.
BACKGROUND OF THE INVENTION
[0002] Thermal coagulation of tissue using RF energy is frequently
being used to treat maladies within the body such as liver tumor
lesions. Physicians frequently make use of catheter-based RF
systems to gain access to interior regions of the body. For
treatment of large lesions, the catheter-based RF systems commonly
employ needle array-type energy delivery devices. However,
depending on the size of the lesion to be ablated and, thus, the
size of the array used to ablate the lesion, many conventional
systems experience difficulty providing an adequate amount of
current to cause tissue heating and coagulation. To address this
problem, many manufacturers simply supply a larger generator to
provide an adequate amount of current to cause tissue heating and
coagulation. Others address the large array problem by having the
user step deploy their array at a measured and stable rate. In such
a procedure, the physician must carefully apply ablating energy to
the element for transmission to the tissue to be ablated, at each
predetermined distance, for a fixed period of time and/or until the
tissue reaches a desired temperature. A heated center is created as
a result, which further heats the target region when the array is
fully deployed. This manual procedure tends to be confusing because
of the multiple parameters that need to be observed prior to moving
on to the next deployment location.
[0003] Physicians may experience other difficulties when the lesion
to be ablated is close to the dermis or is in tissue that is light
in density. When RF catheters or probes are pushed into dense body
tissue such as the liver, the probes tend to be inserted deeply
enough to remain upright during ablation. However, when ablation
procedures, including ablation of some liver lesions, are performed
relatively close to the dermis or are performed in tissue that is
especially light in density, such as the lung, the physician may
have a difficult time maintaining the catheter or probe in its
initial orientation. As a result, the physician must either stack
pads or gauze under the probe or hold the probe in place during the
entire ablation procedure, which is typically about 6-15 minutes.
If the physician chooses not to hold or support the probe during
such procedures, the probe may sag and could push the energy
delivery needles or tines into the dermis layer or other tissue
areas not meant to be ablated.
[0004] Thus, a need exists for controlling the advancement of the
needle array such that the array moves forward to contact new
tissue areas once the tissue area presently in contact is ablated.
In addition, a need exists for maintaining the probe in a desired
orientation for a hands-free mode of operation for the
physician.
SUMMARY OF THE INVENTION
[0005] The present invention is directed to improved systems and
methods that facilitate the automatic deployment and placement of a
needle array for precise ablation of body tissue using RF energy.
The RF ablation system of the present invention tends to eliminate
any confusion as to when the needle array should be farther
deployed into the tissue during step deployment ablation
procedures, minimize the time to carry out such procedures, and
eliminate the need for insertion track bleeding management
techniques following such procedures. In one innovative aspect of
the present invention, a needle array-type energy delivery system
is automatically advanced or step deployed under temperature and/or
impedance feedback control. In another innovative aspect of the
present invention, a catheter based RF ablation system includes an
auto array deployment or advancement system which may comprise a
servo, an electromagnetic, an electro-pneumatic, a hydraulic, or
the like, actuating mechanism, or a stepper motor. In a preferred
embodiment of the present invention, a catheter based RF ablation
system includes a catheter having an elongate tube and a handle
connected to the tube, a needle array slidably received in the tube
and handle, a servo actuated drive mechanism mounted in the handle
and coupled to the needle array, and a control system coupled to
the servo actuated drive and needle array. The control system
preferably comprises a RF energy source, a drive controller, and a
temperature and/or impedance monitoring module for step deployment
at predetermined temperature and/or impedance values. The control
system may also include a timer for step deployment at
predetermined intervals.
[0006] In operation, the catheter is inserted through intervening
tissue until it reaches a treatment site, such as a tumor lesion
within the liver, where the needle array is initially manually
deployed to a first fixed diameter. The RF power source is
activated to a preferred power level while the
temperature/impedance monitoring module of the control system
simultaneously monitors the temperature and/or impedance
measurements coming from the needle array. Once a predetermined
temperature and/or impedance is achieved, the drive controller
activates the servo actuated drive mechanism to advance the needle
array further into the tissue to be ablated. Alternatively, the
drive controller activates the servo actuated drive mechanism to
advance the needle at predetermined intervals. This active
advancing process is repeated, until the array is fully deployed.
Once fully deployed, the needle array acts in accordance with
conventional ablation procedures.
[0007] In another embodiment of the present invention, the system
preferably includes a probe positioning device capable of
maintaining the RF ablation probe in a desired orientation and
preventing the ablation of tissue not meant to be ablated. The
probe positioning device preferably comprises a probe holder
adapted to slidably receive a RF probe and supports connected to
the probe holder. The probe holder being adapted to receive a RF
probe.
[0008] Further objects and advantages of the present invention will
become more apparent from the following detailed description taken
with the following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 shows a plan view of a representative system of the
present invention at a partially deployed state comprising a RF
catheter connected to a control system.
[0010] FIG. 2 shows a plan view of the RF catheter of the
representative system at 25% deployment.
[0011] FIG. 3 shows a plan view of the RF catheter of the
representative system at 50% deployment.
[0012] FIG. 4 shows a plan view of the RF catheter of the
representative system at 75% deployment.
[0013] FIG. 5 shows a plan view of the RF catheter of the
representative system at 100% deployment.
[0014] FIG. 6 shows a plan view of a RF probe with a set of tines
deployed in a patient.
[0015] FIG. 7 shows a plan view of a probe holder of the present
invention holding a RF probe with a set of tines deployed in a
patient.
[0016] FIG. 8 shows an end view of the probe holder of the present
invention.
[0017] FIG. 9 shows a side view of the probe holder of the present
invention.
[0018] FIG. 10 shows an end view of an alternative embodiment of
the probe holder of the present invention.
[0019] FIG. 11 shows a plan view of the alternative embodiment of
the probe holder of the present invention.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0020] Referring in detail to the drawings, an illustrated
embodiment of an improved RF ablation system of the present
invention is shown. Turning to FIG. 1, the illustrated embodiment
shows an overall view of a RF ablation system (10) of the present
invention comprising a RF probe or catheter (12) connected to a
control system (14). The RF catheter (12) preferably comprises an
elongate tube (16) having distal and proximal ends (18) and (19)
and a handle (22) having distal and proximal ends (24) and (26).
The distal end (24) of the handle (22) is connected to the proximal
end (19) of the tube (16). A passageway (not shown) extends through
the tube (16) and handle (22). A needle array (20) having an
elongate shaft (21) is preferably slidably received in the
passageway with a proximal end (23) extending into the handle (22)
and a distal end (25) extending to the distal end (18) of the tube
(16) when in a retracted state and, as the illustrated embodiment
shows, beyond the distal end (18) of the tube (16) when deployed.
The distal end (25) of the shaft (21) of the needle array (20)
preferably splits to form an array of individual tines or needle
electrodes (27) and (29) that are deployable in opposite directions
to maximize ablation lesion size. The tines or needles (27) and
(29) are preferably pre-stressed or pre-bent in a manner known in
the art such that when unrestrained, i.e., deployed beyond the
distal end of the catheter (12), the needles (27) and (29) return
to their bent form.
[0021] Turning to FIGS. 2-5, the needle array (20) of the catheter
(12) is shown with the tines or needle electrodes (27) and (29) at
different stages of deployment. FIG. 2 shows the needle array (20)
at a deployment state of 25%. FIG. 3 shows the needle array (20) at
a deployment state of 50%. FIG. 4 shows the needle array (20) at a
deployment state of 75%. FIG. 5 shows the needle array (20) at a
deployment state of 100%.
[0022] As depicted in FIG. 1, the catheter (12) further includes an
auto array deployment or advancement system (30) adapted to deploy
or retract the individual needles (27) and (29) at the distal end
(25) of the needle array (20). The deployment system (30)
preferably includes a rack or screw drive (31), or some other
driven gear, preferably attached to or formed on the proximal end
(23) of the shaft (21) of the needle array (20), and a driver (28)
mounted in the handle (22) toward its distal end (24). The driver
(28) preferable includes a servo motor (not shown) and a driving
gear (33), such as a spur gear, screw gear, worm gear, or the like,
that is operably coupled to the screw or rack drive (31) on the
needle array (20). Alternatively, the driver (28) may include a
stepper motor or an electromagnetic, electro-pneumatic, hydraulic,
or the like, actuating mechanism. The driver (28) or some other
apparatus (not shown) incorporated into the handle (22) of the
catheter (12) and connected to the needle array (20) may be
manually manipulated to deploy or retract the needles (27) and (29)
to a desired position. The catheter (12) may also include
mechanical stops or detents located internally within the handle
(22) that provide the user with tactile feel as to the positioning
of the needles (27) and (29) when they are manually advanced.
[0023] For example, such tactile feel may be provided by a spring
plunger with a ball detent built into the handle (22) wherein the
spring loaded ball would ride along a smooth wall of an i inner
handle. Recess or detent locations would be calibrated along the
inner handle to deploy the array a predetermined diameter.
Alternatively, a tab or o-ring connected to the inner surface of an
outer handle could be used to locate recesses or detents formed on
the inner handle. Another alternative may include radial grooves on
an inner or outer handle that enables the probe to be rotated and
held in place after the array have been deployed a predetermined
diameter. T
[0024] The control system (14) preferably comprises a RF power
source (38), such as a generator, a drive controller (42) coupled
to the power source (38), an impedance and/or temperature
monitoring module (40) coupled to the power source (38) and the
drive controller (42), and a variety of displays to indicate
temperature, impedance, needle position, elapsed time, and the
like. The drive controller (42) may be built into the RF generator
or may be a stand alone unit. A first cable (32), interconnected to
the power supply (38), extends from the control system (14) to the
proximal end (23) of the shaft (21) of needle array (20) to supply
RF power to the needles (27) and (29) of the needle array (20). A
second cable (34), interconnected to the monitoring module (40),
extends from the control system (14) to the proximal end (23) of
the needle array (20) to communicate temperature or impedance
measurements from the needles (27) and (29), which preferably
include temperature and/or impedance measuring capabilities. A
third cable (36), interconnected to the drive controller (42),
extends from the control system (14) to the servo motor of the
driver (28) in the handle (22) of the catheter (12) to control or
actuate the driving gear (33), which in turn causes the deployment
or retraction of the needle array (20).
[0025] The RF ablation system (10) of the present invention is
preferably operated in a manner that increases the current density
applied to the tissue to be ablated. The system (10) preferably
uses impedance or temperature feedback to control the servo
actuated array deployment mechanism (30) resulting in the automated
step deployment of the needle array (20). Because the deployment of
the needle array (20) is fully automated, any confusion associated
with conventional step deployment methods used with conventional
needle array-type devices tends to be eliminated.
[0026] In operation, the distal end (18) of the catheter (12) is
inserted through intervening tissue until it reaches a treatment
site, such as a tumor lesion within the liver. Once the distal end
(18) of the catheter (12) is in place, the needle array (20) is
preferably manually deployed to extend the needles (27) and (29) to
a first fixed diameter. If the device includes internal detents or
steps, the needle array (20) is advanced until a step or detent is
encountered. With return electrodes properly in place on the
patient, the RF generator of the power source (38) is activated to
a preferred power level while the temperature/impedance monitoring
module (40) of the control system (14) simultaneously monitors the
temperature and/or impedance measurements coming from the needles
(27) and (29). Once a predetermined temperature and/or impedance is
achieved, while RF power is still being delivered, the drive
controller (42) of the control system (14) activates the servo
motor of the driver (28) and, thus, actuates the driving gear (29)
to advance the needle array (20) forward a predetermined distance
and, thus, advance the needles (27) and (29) further into the
tissue to be ablated. Alternatively, the needles (27) and (29) may
be advanced further into the tissue to be ablated after a
predetermined period of time has elapsed. This active advancing
process is repeated, as shown in FIGS. 2-5, until the array (20) is
fully deployed as shown in FIG. 5. Once the needle array (20) is
fully deployed, the needle electrodes (27) and (29) act in
accordance with conventional ablation procedures.
[0027] After completion of the ablation procedure, the needle array
(20) may be automatically fully retracted into the elongate tube
(16) of the catheter (12) prior to retrieval of the catheter (12).
Alternatively, the needle array (20) may be retracted automatically
to a partially deployed state in which the needles (27) and (29)
extend slightly beyond the distal end (18) of the catheter (12). In
the partially deployed state, the catheter (12) may be retrieved
while the needle array (20) ablates the catheter insertion track to
minimize or eliminate post procedure bleeding along the insertion
track.
[0028] As indicated herein, the RF ablation system (10) of the
present invention advantageously tends to 1) eliminate any
confusion as to when the needle array (20) should be further
deployed into the tissue, 2) minimize the time to carry out such
procedures, and 3) eliminate the need for gelfoam or comparable
insertion track bleeding management techniques.
[0029] When RF probes, such as the catheter (12) of the present
invention, are pushed into dense body tissue such as the liver, the
probes tend to be inserted deeply enough to remain upright during
ablation. However, some ablation procedures, including the ablation
of some liver lesions, are performed relatively close to the dermis
or may be performed in tissue that is especially light in density,
such as the lung. As a result, the probe or catheter (12) may have
a difficult time maintaining the orientation initially set up by
the physician, requiring the physician to hold the probe in place
during the entire ablation procedure, which is typically about 6-15
minutes, or stack pads or gauze under the probe to support the
probe. If the physician chooses not to hold or support the probe
during such procedures, the probe may sag and could push the
needles (27) and (29) into the dermis layer or other tissue areas
not meant to be ablated. For example, FIG. 6 shows the catheter
(12) of the present invention inserted into a patient P at a
relatively shallow depth with at least one of the tines (27) and
(29) being deployed relatively close to the dermis of the patient
P. If the catheter (12) were to sag, the energy delivery needles or
tines may be pushed into the dermis layer or other tissue areas not
meant to be ablated.
[0030] To assist in the deployment of the RF catheter (12) of the
present invention and avoid ablating tissue not meant to be
ablated, the present invention further includes a probe positioning
device (100). As depicted in FIG. 7, the probe positioning device
(100) is capable of propping the catheter (12) up and holding it in
a desired upright orientation. The positioning device (100)
includes a holder (110) adapted to slidably receive the handle (22)
of the catheter (12) and two side support members (112) adapted to
rest on the patient P. As shown in FIG. 9, the holder (110) is
pivotably connected to the support members (112) via a pair of
protrusions or shafts (114) extending inwardly from the support
members (112). The holder (110) and support members (112) have a
friction fit or may include a ratchet mechanism or the like there
between to releasably lock the holder (110) in a desired
orientation.
[0031] As depicted in FIG. 8, the holder (110) includes a
semi-annular body (120) having an opening (122) that is slightly
smaller than the diameter of the handle (22) of the catheter (12)
of the present invention. The body (120) of the holder (110) is
preferably formed from a semi-compliant material to enable the
handle (22) of the catheter (12) to snap into place within the
holder (110).
[0032] In an alternative embodiment shown in FIGS. 10 and 11, the
positioning device (200) may be fabricated as a thermoformed insert
to be inserted into a thermoformed tray. The positioning device
(200) includes a holder (210) and a support (212). The holder (210)
includes a body (220) having a substantially circular passageway
(221) adapted to slidably receive the handle (22) of the catheter
(12) of the present invention. The body (220) further includes an
opening (222) having a width that is slightly smaller than the
diameter of the handle (22) to allow the handle (22) to be snapped
into place within the passageway (221).
[0033] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof have been shown
in the drawings and are herein described in detail. It should be
understood, however, that the invention is not to be limited to the
particular form disclosed, but to the contrary, the invention is to
cover all modifications, equivalents, and alternatives falling
within the spirit and scope of the appended claims.
* * * * *